3pipes hot,one not

[dragxs11]

What model do you have mike?
Rich on #2 if I read correctly?
I have 2 top-o-head ideas...
Could be sucking gas in through the vac actuated fuel valve that is usually connected to intake #2 if it is leaking. Cap it off and run on prime, replace #2 plug and see if anything changes.

While you ready the plug to start, keep an eye on the bottom of your air box, maybe best to take the lower half of it off. if fuel makes its way out the back of the carb, looks like your float is hanging up. I had this happen once cuz I reused the float bowl gaskets and pressed them into the float so they couldn't move.

Sound plausable guys?

[firecrackerboom]

Originally posted by AlanB


It isn't the coil 'cos the other cylinder fired by the coil is OK.

All the info you need is in V. recent posts.........

AlanB

What is "V. recent posts" ?

[DiverRay]

What is "V. recent posts" ?

View recent posts, You can also do a "search" on spark. I would think you need to check the spark plug caps. Verify no more than 5K Ohms of resistance. you may also need to cut about 1/4" off the end of the spark plug wire, after unscrewing the cap. This will clean it up, and may fix the problem.

[trbig]

For a quick check to see if it's the wires... swap the #1 & 4 spark plug wires to the spark plugs. You can do this between #2 &3 also. If #4 suddenly comes to life... new wires, or as Ray suggested, just trim the ends a bit and try it again.


Tod

[GrandPrix46]

I'm having the same problem with cyl #3, swapped plug and wire from cyl #2 and still the #3 primary doesn't get hot. Fuel on the plug as well. With spark, and fuel, something should happen...

[newc4]

My #3 cylinder is also running cold at speed on my SF. (Usually the problem is with the pilot jet). I did the #2-#3 sparkplug swap and #3 remained cold. This would lead me to believe that I’ve a problem with the float valve but I did get a hot pipe with the choke circuit. I’ll check for vacuum leaks but I’ve done that before and had no problems there. Next, I’ve 2 colortune sets; I’ll put them in #3 and #4 so I can observe the flame front at all RPMs.

I just don’t want to clean the carbs again.

Darrell

[newc4]

I ran my SF with colortune plugs in #3 and #4. With the choke on, flame was observed in both cylinders. As soon as I closed the choke, #3 lost flame. So, I know the starter circuit works, appears that the pilot and main jets are not. OK, the carbs are coming off. After I had them off I drained the bowls. All had gas so I know the float needle valves are letting gas into the bowls.

Took out the float and needle, the float doesn’t appear to have any leaks.

To out the pilot jet and I couldn’t see through the tip so I cleared that with a blast of carb cleaner. Now, I have visibility through all the pilot jet holes. Took out the air mixture screw and I can see through the single orifice. Main jet passes the visual test.

I proceeded to blow out all the passages with carb cleaner and noted no apparent obstructions. Should the pilot jet affect operation at higher throttle settings?

Checked the diaphragm and noted no holes or tears.

So I’m scratching my head wondering why I get no gas at the higher throttle settings. Even with a plugged pilot jet, the main jet should work - is that right?. Float height? I’ll check that and then put it back together to see how it runs. Lemme see, I think this is my third time.

Darrell

[mro]

closed the choke, #3 lost flame.

Pretty much points to pilot.
Check how far out #3 is (stock air box/exhaust 1 1/4 to 2 turns out is normal)
More turns out = more fuel/air
Synk carbs
Adjust pilots.
Check #3 if firing
Synk agin
____
Mains kick in above 2000/2500 rpm
____
Float level affects ALL rpm ranges.
Should NOT deveate from stock settings unless all else fails.


mro

[newc4]

Took the carbs off, cleaned up #3, colortuned - richened the mixture a bit - synched the carbs and adjusted the idle. Need to adjust the idle up but otherwise it ran like a top. A little stuttering at the low end but that is working itself out. We should be good to go for XSEast.

Darrell